The present invention relates to digitizers. More particularly, the present invention relates to devices for use with presentation boards and pens for digitizing lines drawn manually thereon.
Throughout the last decade the presentation of data in a group setting has become highly digitized, involving the use of technologically advanced audio-visual devices. As such, the use of a conventional drawing board, such as a whiteboard, in such presentations has rapidly declined.
Still, some presenters often prefer to use a marker and whiteboard to present and develop ideas during group sessions. To enable recording of information presented by such means, several digitized whiteboard systems have been developed.
Such systems typically employ a combination of transmitters and receivers for processing signals from a handheld device. The writing movements produced by these devices are traced and recorded, and as a result the textual and graphical content of a session can be digitized and ported to a computer.
Various techniques are used for determining the position of a handheld device or stylus on a flat surface. U.S. Pat. No. 4,564,928 to Glenn et al., U.S. Pat. No. 4,886,943 to Suzuki et al., U.S. Pat. Nos. 4,910,363 and 5,073,685 to Kobayashi et al. and U.S. Pat. No. 5,097,102 to Yoshimura et al. all disclose systems in which a vibrating element associated with a pen transmits vibrations through the material of a board. The vibrations are detected by transducers attached to the board and the position of the pen is calculated from the transmission time of the vibrations through the board. These systems inherently function exclusively when the pen is in contact with the board such that vibrations are transferred to the board. As a result, no special mechanism is required to distinguish writing from non-writing pen movements.
These systems are generally inaccurate due to non-uniform transmission times through the board. In fact, they typically require highly specialized board structures which renders them expensive and inconvenient.
An alternative approach is the use of air-borne ultrasound signals. Examples of such systems are described in U.S. Pat. No. 4,777,329 to Mallicoat, U.S. Pat. No. 4,814,552 to Stefik et al., U.S. Pat. No. 4,506,354 to Hansen U.S. Pat. No. 4,758,691 and to De Bruyne and PCT/IL98/00093, filed Feb. 25, 1998 by Pegasus Technologies Ltd., which is incorporated by reference as if fully set forth herein.
These systems employ various combinations of ultrasound transmitters and receivers arranged at two points fixed relative to a board and on a movable writing implement. The position of the movable implement is then derived by triangulation. These systems typically require an additional hard-wired or electromagnetic link, such as an infrared link, between the movable implement and a base unit to provide timing information for time-of-flight ultrasound calculations. An additional switch is also required to identify when the movable element is in contact with the board.
These systems are typically limited to relatively small boards. This is because of signal-to-noise ratio (SNR) limitations which interfere with obtaining accurate measurements. The volume of ultrasound used cannot be very high without causing bothersome accompanying whistling noises. Additionally, in a wireless system, power considerations severely limit the transmitted volume. In order to generate reliable position information, the transmitter-to-receiver distance must therefore be kept small. Attempts to use different sets of receivers for different regions of a large board generally result in discontinuities when the movable element travels from one region to another.
Another shortcoming of these systems is their inability to reproduce rapid interrupted pen strokes such as performed when drawing a dashed line. Typically, the transmitter or receiver element in the pen turns off when the pen is inactive and is re-activated each time the pen comes in contact with the board. The system then takes a fraction of a second to resynchronize before it responds correctly. In the case of short strokes, the length of the operative stroke may be comparable with the response time of the system, thereby giving very poor results.
An additional problem of some of the airborne ultrasound digitizer systems is that the ultrasound transmitter or receiver element is mounted asymmetrically to the side of the drawing implement or stylus. As a result, the measured position is offset from the true drawing position in a direction which changes with rotation of the drawing implement. This may result in discontinuities and illegible writing in the digitized image when the drawing implement position is changed between strokes.
Furthermore, conventional presentation board digitizer systems are typically limited to use with specially produced writing implements. This renders them expensive since pens have a very limited lifetime. Even where the ink cartridge is separately replaceable, the components used must be of a very specific design to be compatible.
Finally, styluses which employ a color writing tip are usually restricted to using a single color tip and cannot employ different colors or a tip of a different function, since the recordation system cannot distinguish between the different tips.
There is therefore a need for a reliable, low-cost, digitizer system which may be used with conventional presentation boards of all sizes for determining accurately the position of a drawing implement on the board. Additional needs and improvements provided by the present invention are described in the specification that follows.
According to one aspect of the present invention there is provided a handheld device for use with a board supplemented with a processing system for digitizing operative strokes of the handheld device on the board, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving a portion of a body of a drawing implement with its drawing tip extending from the central orifice, the housing being formed with a plurality of openings being circumferencly arranged at the distal end of the housing and communicating with the bore; and (b) an ultrasonic receiver or transmitter device mounted within the housing, remote from the drawing tip, yet in close proximity with the bore, the device being for receiving or transmitting an intermittent ultrasound signal through the bore and the plurality of openings, thereby enabling triangulation of the drawing tip.
According to another aspect of the present invention there is provided a handheld device for use with a board supplemented with a processing system for digitizing operative strokes of the handheld device on the board, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving and releasing a portion of a body of a removably attachable drawing implement through the orifice with its drawing tip extending from the central orifice; (b) a retainer in the housing for releasably retaining the removably attached drawing implement within the housing; (c) an ultrasonic receiver or transmitter device being internally or externally connected to the housing for receiving or transmitting an intermittent ultrasound signal; (d) a microswitch in the housing being actuated when contacted by a proximal end of the body, so as to be responsive to a force exerted on the drawing tip of the drawing implement; and (e) an electronic circuitry being in the housing and electronically communicating with the microswitch for affecting operation of the device at least when the microswitch indicates that the force is exerted on the drawing tip of the drawing implement.
According to yet another aspect of the present invention there is provided a handheld device for use with a board or screen supplemented with a processing system for digitizing operative strokes of the handheld device on the board or screen, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving and releasing a portion of a body of a removably attachable operative implement through the orifice with its operative tip extending from the central orifice, the operative implement being selected from the group consisting of a drawing implement and an annotation implement; (b) a retainer in the housing for releasably retaining the removably attached operative implement within the housing; and (c) an ultrasonic receiver or transmitter device being externally or internally connected to the housing for receiving or transmitting an intermittent ultrasound signal.
According to still another aspect of the present invention, in a board or screen digitizing system including at least three spaced apart ultrasound receivers associated with the board or screen surface, and a handheld device including an intermittent signal transmitter, there is provided a method of tracking the handheld device, the signals being transmitted with a preset first interval therebetween, the method comprising the steps of collecting a plurality of time non-referenced ultrasound signals by each of the at least three spaced apart ultrasound receivers and calculating a position of the handheld device for each of the time non-referenced ultrasound signals, thereby tracking the handheld device. Preferably, reception of each of the at least three spaced apart ultrasound receivers is suspended for a second time interval following the reception of a signal thereby, the second time interval is shorter than the first time interval.
According to an additional aspect of the present invention there is provided a handheld device for use with a board or screen supplemented with a processing system for digitizing operative strokes of the handheld device on the board or screen, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving and releasing a portion of a body of a removably attachable operative implement through the orifice with its operative tip extending from the central orifice and being selectable among a plurality of different operative implements; (b) a retainer in the housing for releasably retaining the removably attached operative implement within the housing; and (c) an ultrasonic transmitter device being internally or externally connected to the housing for transmitting one of a plurality of intermittent ultrasound signals, each of the plurality of intermittent ultrasound signals having a different frequency, each of the frequencies being associated with one of the plurality of different operative implements; and (d) a controller on or in the housing for setting the transmitter device to transmit an intermittent ultrasound signal of a frequency corroborating with one of the plurality of different operative implements.
According to a still additional aspect of the present invention there is provided a handheld device for use with a board or screen supplemented with a processing system for digitizing operative strokes of the handheld device on the board or screen, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving a portion of a body of an operative implement with its operative tip extending from the central orifice; (b) an ultrasonic transmitter device being internally or externally connected to the housing for transmitting one of two intermittent ultrasound signals, each of the two intermittent ultrasound signals having a different frequency; (c) a microswitch in the housing being in a first mode or a second mode, the microswitch being in the first mode when in contact with a proximal end of the body and in the second mode when not in contact with the proximal end of the body; and (d) an electronic circuitry electronically communicating between the microswitch and the transmitter device, the electronic circuitry being for associating one of the first and second modes with the transmitter device, such that the intermittent ultrasound signals of the different frequency are transmitted by the transmitting device in a mode dependent manner, thereby informing the processing system whether the operative tip is in contact with, or removed from, the board or screen.
According to a yet additional aspect of the present invention there is provided a handheld device for use with a board or screen supplemented with a processing system for digitizing operative strokes of the handheld device on the board or screen, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving a portion of a body of an operative implement with its operative tip extending from the central orifice, at least a longitudinal portion of the housing originating at the distal end of the housing being of an infrared conveying material; (b) an ultrasonic receiver or transmitter device being internally or externally connected to the housing for receiving or transmitting an intermittent ultrasound signal; (c) an infrared transmitter device being implemented at a proximal end of the longitudinal portion of the housing, the infrared transmitter device being designed for directing infrared radiation emitted thereby through the longitudinal portion of the housing.
According to further features in preferred embodiments of the invention described below, the longitudinal portion of the housing is supplemented with an infrared reflector for reflecting the infrared radiation out of the housing.
According to a further aspect of the present invention there is provided a handheld device for use with a board or screen supplemented with a processing system for digitizing operative strokes of the handheld device on the board or screen, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving a portion of a body of an operative implement with its operative tip extending from the central orifice; (b) an ultrasonic receiver or transmitter device being internally or externally connected to the housing for receiving or transmitting an intermittent ultrasound signal; (c) a pressure sensitive microswitch in the housing being actuated when pressured by a proximal end of the body, so as to be responsive to a force exerted on the drawing tip of the drawing implement; and (d) an electronic circuitry being in the housing and electronically communicating with the microswitch for affecting operation of the device at least when the microswitch indicates that the force is exerted on the drawing tip of the drawing implement.
According to a still further aspect of the present invention there is provided a remotely controlled handheld device for use with a board or screen supplemented with a processing system for digitizing operative strokes of the handheld device on the board or screen, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving a portion of a body of an operative implement with its operative tip extending from the central orifice; (b) an ultrasonic receiver or transmitter device being internally or externally connected to the housing for receiving or transmitting an intermittent ultrasound signal; and (c) a remote signal receiver for receiving operational command signals from a remote signal transmitter being controlled by an operator.
According to yet a further aspect of the present invention there is provided a handheld device for use with a board or screen supplemented with a processing system for digitizing operative strokes of the handheld device on the board or screen, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving a portion of a body of an operative implement with its operative tip extending from the central orifice; and (b) a transparent ultrasonic receiver or transmitter device being connected to the housing and surrounding the operative tip for receiving or transmitting an intermittent ultrasound signal, thereby rendering the operative tip visible to a user.
The present invention successfully addresses the shortcomings of the presently known configurations by providing a plurality of improvements to handheld devices for use with a board or screen supplemented with a processing system for digitizing operative strokes of the handheld devices, which improvements are further addressed in the following sections of the specification.